feat: Initial Hub implementation

Complete LetsBe Hub service for license management and telemetry:

- Client and Instance CRUD APIs
- License key generation and validation (lb_inst_ format)
- Hub API key generation (hk_ format) for telemetry auth
- Instance activation endpoint
- Telemetry collection with privacy-first redactor
- Key rotation and suspend/reactivate functionality
- Alembic migrations for PostgreSQL
- Docker Compose deployment ready
- Comprehensive test suite

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Dockerfile

@@ -0,0 +1,24 @@
+FROM python:3.11-slim
+
+WORKDIR /app
+
+# Install system dependencies
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    gcc \
+    libpq-dev \
+    && rm -rf /var/lib/apt/lists/*
+
+# Copy requirements first for better caching
+COPY requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+# Copy application code
+COPY . .
+
+# Create non-root user
+RUN useradd -m -u 1000 hub && chown -R hub:hub /app
+USER hub
+
+EXPOSE 8000
+
+CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]